Problem: $ { \left[\begin{array}{rrr}{2} & {0} & {2} \\ {-1} & {-2} & {1}\end{array}\right]-\left[\begin{array}{rrr}{3} & {4} & {0} \\ {1} & {2} & {1}\end{array}\right] = {?} } $
Explanation: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rrr}{2}-{3} & {0}-{4} & {2}-{0} \\ {-1}-{1} & {-2}-{2} & {1}-{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{-1} & {-4} & {2} \\ {-2} & {-4} & {0}\end{array}\right]}$